Answer to Question 11
There may be no connection between the proposed warning pain and disk degeneration. Degeneration is an ageing effect and evolution will presumably minimise it. The warning pain will be enhanced by evolution to make it effective.
On the other hand, the mechanism of degeneration may be an essential part of the warning pain. It appears that degeneration starts with cracks in the posterior annulus. The nucleus to some extent "leaks" outwards along these cracks while nerves grow inwards from the periphery along the same cracks.
This might be the mechanism by which the back pain causing nerves come into direct contact with the material of the nucleus.
It could even be argued that evolution will have accelerated the tendency for degeneration in human discs because it is a necessary part of the back pain which protects the spine against the mechanical collapse (and consequent prolapse) described in the answer to question 5
Thus, an L4/5 or L5/S disk that is flexing beyond parallel sided may be “leaking” via the cracks that provide access to the nerves in the posterior-lateral annulus. If this is part of the mechanism of degeneration then limiting the flexion to the natural limit may keep the nucleus away from these cracks, reduce or stop the leaking, and allow the disk to become less degenerated. There is evidence that this is seen on follow up after various immobilizing interventions such as Graf ligament.